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Sending data in cgi

Sending data in cgi






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    Sending data in cgi Sending data in cgi Presentation Transcript

    • Sending Data Using an Online Form CISIWEB 430A
    • Objectives
      • In this unit, you will
        • Plan and create a CGI script that processes form data
        • Learn how to prevent Perl from creating undeclared variables in a script
        • Declare (create) scalar variables in a script
        • Use assignment statements to assign values to existing variables
        • Send form data to a script using GET and POST
        • Improve the appearance of numbers displayed on a Web page
    • <html> <head> <title>Chapter 3 - Parsing Data</title> </head> <body bgcolor=&quot;#FFFFFF&quot;> <form action=&quot;http://myServer/parse2.cgi&quot; METHOD=POST> Comment <input type=&quot;text&quot; name=&quot;myComment&quot;> <p> <input TYPE = &quot;submit&quot; value = &quot;Submit&quot;> <input TYPE = &quot;reset&quot; VALUE = &quot;Start Over&quot;> </p> </form> </body> </html> #!/usr/bin/perl use CGI qw(:standard); print &quot;Content-type: text/html &quot;; print &quot;<HTML><HEAD><TITLE>Chapter 3&quot;; print &quot; - Output</TITLE></HEAD><BODY> &quot;; print param('myComment'); print &quot;</BODY></HTML>&quot;;
    • Planning the script
      • Plan the HTML page
      • Plan the logic for the script
      • Plan the information the script will output
    • Accessing Form Data
      • In an HTML form, the keys are the names of the form elements, and the values are the information (usually) entered by a user.
      • When the user presses the “Submit” button, the data are automatically transmitted to the script.
      • Once the data are sent, our script needs to parse the data so that we can use it.
        • If we use the CGI.pm module, parsing the data from a form is identical to parsing the data from a hyperlink.
    • Creating the Form
      • Use HTML to create the form
        • FORM tag contains instructions
          • Action = location of .cgi
          • Method = Get or Post
          • Submit – calls the action to happen
          • Controls – include a name attribute
    • Get vs. Post
        • GET appends the form data to the end of the URL specified in the action property and is similar to sending the data through a hyperlink
        • POST sends the data as a separate data stream, allowing the Web server to receive the data through “STANDARD INPUT”
    • Including special characters
      • This project uses a dollar sign, which can’t be typed in directly (why not?)
      • Characters that are given special meaning within a regular expression
      • Backslash if you want to use literally
        • :. * ? + [ ] ( ) { } ^ $ |
        • Any other characters automatically assume their literal meanings.
    • Using printf
      • Printf function is used for displaying data on a Web page
        • Allows you to format the information
        • Allows you to specify the number of decimal places
        • Allows you to display a + or – before the number
        • Syntax: printf formatstring, list;
          • List is a comma separated list of items
          • Formatstring contains text and one or more format fields
    • Parts of a format field
          • % - required, at the beginning of a format field
          • Modifier – optional (+ or – to denote a positive or negative number)
          • Minimum field width – option, sets a min number of characters to display
          • Precision – optoin, expressed as a period followed by a number, the number of digits to the right of the decimal
          • Format type – required – d (decimal) or f (floating point)